1. Field of the Invention
The present invention relates to an interference cancellation/removal system, apparatus and method which can reduce inter-user interference when simultaneous transmissions to the same base station are repeated from two or more wireless users using the same time frequency resource.
2. Description of the Related Art
In mobile communications, interfering signals that hamper reception quality can result from a number of sources.
In a wireless communication system when two users transmit simultaneously in the same cell to a base station, their transmissions can interfere with each other. When both users use the same time-frequency resource, their transmissions interfere with each other.
Moreover, if both users repeat the transmission of the same symbols in subsequent slots, the desired signals may be combined coherently by the base station, but both interference and noise will be combined non-coherently, thus causing interference.
Furthermore, if the channels for the two users do not change across repeated transmissions, both the desired signals and the interference will be combined coherently by the base station, but the noise will still be combined non-coherently. Therefore, the interference from the other signal will result in close to an one hundred percent error rate.
Accordingly, we have realized that there is a need for techniques to mitigate interference during the operation of wireless communication system.